JPH0391678A - Operation control system for cold air circulation type showcase - Google Patents

Abstract

PURPOSE:To reduce a defrosting time by providing a fan unit with at least three blast fans, determining the pattern of the number of the operating blast fans corresponding to the operation mode of cold keeping, defrosting or pulling- down and changeover-controlling the operations of the blast fans. CONSTITUTION:During cold keeping, a cooler 5 and blast fans 7A and 7C are operated and, in this condition, the cold air is blasted in circulation inside a showcase to keep goods accommodated in a showcase cold. When an operation mode is changed over from the cold keeping to defrosting at a given period by a timer control or the like, the cooler 5 is stopped, a defrosting heater 6 is changed over to be electrified, a blast fan 7B that has been stopped is changed over to be operated and all the blast fans 7A, 7B and 7C are operated at the same time. Therefore, the large amount of the air ventilates in a circulating blast duct and, in this process, the defrosted warm air heated by the defrosting heater 6 removes frost attached to the surface of the cooler 5. Thus, a defrosting time can be sharply reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an operation control system for a cold air circulation type showcase that employs a heater defrosting system.

[Conventional technology]

First, in Fig. 4, which explains the configuration of a flat open showcase to which the present invention is applied, l is a case main body with an open top surface, and an outer box 2 and an inner box 3 of the case main body l. A cold air circulation duct 4 partitioned between the duct 4 and the duct 4 includes a cooler 5 (evaporator of the refrigerator), a defrosting heater 6. A fan unit 7 including a plurality of blowing fans is housed.

Note that 8 is a temperature sensor that detects the air temperature on the outlet side of the cooler 5.

With such fJl power, the cooler 5. By operating the blower fan of the fan unit 7, cold air cooled by heat exchange with the cooler 5 is circulated through the cold air circulation duct 4 as shown by the arrow in the figure, and the cold air is circulated through the upper opening of the case body l. Blow and form the curtain. As a result, inner box 3
The products (not shown) stored in the inner refrigerator are kept cool while shielding the space between the interior of the refrigerator and the outside air with an air curtain.

On the other hand, when the operation mode is switched from cold storage to defrost at a predetermined period due to timer control, etc., the cooler 5 is stopped while the blower fan of the fan unit 7 continues to operate at a constant speed, and the defrost heater 6 is energized. The warm defrosting air heated by the heater is blown to the cooler 5 to melt and remove frost adhering to the surface of the cooler. Here, when the temperature of the cooler 5 or the air temperature on the outlet side of the cooler rises to a predetermined defrosting end temperature (0°C or higher) as defrosting progresses, the detection signal from the temperature sensor 8 is detected. Defrost is finished and defrost heater 6 is turned on.
It is well known that the energization of the refrigerator is stopped, the refrigerator is restarted, and the operation mode is switched back to cold storage operation.

[Problem to be solved by the invention]

By the way, in the above-mentioned heater defrosting method, since the warm defrosting air heated by the heater is circulated and ventilated during the defrosting period, the influence of the warm defrosting air is exerted on the products stored in the refrigerator through the opening on the top surface of the case body. Also, the product temperature gradually rises as the defrosting time passes. Here, the changes in temperature of the cooler and product corresponding to each operation mode of cold preservation and defrosting are shown in Fig. 5. In the figure, A indicates the temperature of the cooler, B indicates the product temperature, and Hl on the time axis.
is the defrosting start time, 82 is the defrosting end time, T1 on the temperature axis is the cold storage temperature of the cooler, T2 is the cold storage temperature of the product,
710 and 720 are coolers associated with defrosting.

Indicates the rising temperature of the product.

As is clear from FIG. 5, when the operating mode of the showcase is switched from cold preservation to defrosting, the cooler temperature A rises, and the product temperature B also gradually rises accordingly. Then, at time H2, when defrosting is switched back to cold storage, the temperature of the cooler begins to drop to the upper limit of temperature TIO at the end of defrosting, and then, at time H4, it almost reaches the predetermined cold storage temperature T1. .

By the way, during the pull-down period immediately after the resumption of cooling, the cooler temperature A has not decreased sufficiently, and the v11 ring air still retains defrosting heat. For this reason, in the conventional operation control method in which the blower fan of the fan unit is operated at a constant speed throughout the period of cooling and defrosting as described above, the product temperature B continues to rise until time H3 even after the defrosting end time H2. In addition to the rise in temperature T20 of the product temperature B becoming considerably higher than the cold storage temperature T2, there is also a pull-down time from the time H2 when the cold storage operation is restarted until the product temperature B falls to the predetermined cold storage temperature T2. It will also take a long time.

As mentioned above, in cold air circulation type showcases, when defrosting, the cooler is stopped and the defrost heater is energized to circulate air, so the temperature of the products will rise to some extent. However, in this case, the greater the increase in product temperature and the longer the increase time, the earlier the quality of the product deteriorates. Therefore, from the perspective of maintaining the long-term quality of products, how to reduce the rise in product temperature due to defrosting and how to shorten the defrosting time is a major challenge for showcase operation control. It has become.

The present invention has been developed in consideration of the above points, and in addition to shortening the defrosting time, it is possible to maintain the quality of the product by minimizing the rise in temperature of the product during the defrosting period. The purpose of this invention is to provide an operation control method for a cold air circulation type showcase.

[Means to solve the problem]

In order to solve the above problems, the present invention includes at least three or more blowing fans in a fan unit for circulation blowing, and a pattern of the number of blowing fans that corresponds to each operation mode of cooling, defrosting, and pull-down. Defrosting>Cold storage>Pull-down settings shall be established, and the operation of each blower fan shall be switched and controlled in accordance with the operating mode of the showcase.

[Effect]

In the above, if the number of blower fans installed in the fan unit is three, two blower fans will be operated together with the cooler during cold storage. Then, when the operation mode switches from cold storage to defrost, the cooler is stopped and the defrost heater starts energizing, and all the blower fans (3 units) are operated, including the fans that were stopped during cold storage. Switch as follows. This increases the amount of circulating air and therefore the amount of warm defrosting air sent to the cooler, which speeds up the progress of defrosting and completes the defrosting process in a short time without leaving any remaining frost. . In addition, after defrosting is completed, the defrost heater is stopped and the cooler is restarted, and the period (pull-down) until the cooler temperature drops to the predetermined cold storage temperature is maintained.
Then, the number of operating blower fans is the number of operating fans during cold storage (2 units).
Switch to a smaller number (1 unit). As a result, during the pull-down period, the minimum amount of air curtain required to block outside air is blown out from the opening of the case body, and the amount of circulating air inside the refrigerator is kept low. As a result, the influence of the remaining V1 warm air immediately after defrosting on the rise in product temperature in the warehouse is reduced, so the product temperature will hardly rise further, and the amount of air blown to exchange heat with the cooler is reduced. This allows the cooler to drop to the predetermined cold storage temperature in a short period of time. Then, when the pull-down mode returns to the cold storage operation, the number of operating fans increases to two, and the temperature of the products in the refrigerator rapidly drops to the predetermined cold storage temperature.

〔Example〕

Figure 1 is a time chart showing the operation control of the embodiment of the present invention, Figure 2 is a pattern diagram of the number of operating fan units corresponding to each operation mode of the showcase, and Figure 3 is the change in cooler temperature and product temperature. FIG.

First, the fan unit 7 built into the showcase shown in FIG. 4 is equipped with at least three blower fans 7A and 78.7C as shown in FIG. Operation is controlled individually. Note that the controller 9 also controls the refrigerator of the cooler 5 shown in FIG. 4 and the defrosting heater 6 at the same time in accordance with the operating mode of the showcase. And cold storage and defrosting as described below.

According to each pull-down operation mode, the cooler 5. The defrosting heater 6 and each blower fan of the fan unit 7? A.

7B, ? The operation of C is controlled. In addition, in FIG. 2, the symbols ON and OFF attached to each blower fan represent the operation and stop states of the fan, respectively.

In other words, during cold storage, the blower fan 7^ is used together with the cooler 5.
, 7C is operated, and in this state, cold air is circulated inside the refrigerator to keep the products stored in the refrigerator cold.The operation mode of the lower case is changed from cold preservation at a predetermined period by timer control, etc. When the state changes to frost, the cooler 5 is stopped and the defrost heater 6 is switched to energization, and the blower fans 7B, which have been stopped until now, are switched to operation to operate all the blower fans 7A.

Operate 7B and 7C at the same time. As a result, a large amount of air is passed through the circulation ventilation duct, and in this process, the defrosting heater 6
Exclusion nI heated with! The air removes frost adhering to the surface of the cooler 50. When the frost on the cooler 5 is removed and the temperature of the cooler 5 rises to the defrosting end temperature, the temperature sensor 8 (see FIG. 4) senses this state, and based on the signal, a command is issued from the controller 9. At this point, the power supply to the defrosting heater 6 is stopped, and the operation of the refrigerator is restarted to proceed to the next pull-down. During this pull-down period, the blower fans 7A and 7C of the fan unit 7 are switched to stop, and only the blower fan 7B is operated. As a result, the amount of circulating air is minimized, and the temperature of the cooler 5 is rapidly lowered while blowing out and forming the minimum air curtain necessary for shielding the outside air from the upper surface opening of the case body. When the temperature of the cooler 5 (actually the temperature of the circulating air that exchanges heat with the cooler 5) drops to a predetermined cooling temperature, at this point the fan units 7 return to the cooling operation number pattern according to a command from the controller 9. , the blower fans 7A and 7B are operated, and the blower fan 7B is switched to a stopped state. As a result, the showcase shifts to a steady cold storage operation state.

By controlling the operation of the showcase mentioned above, the cooler temperature,
The product temperature follows the changes shown in Figure 3. Comparing Figure 3 with Figure 5, which shows the transition of temperature changes according to the conventional operation control method, the defrosting time (Ill-)12) from the start to the end of defrosting, and the cooling from the end of defrosting. The pull-down time (H2~!14) for the product temperature A to drop to the predetermined cold storage temperature T1 is significantly shortened, and along with this, the rise in product temperature B during defrosting (T2O-72
), and the time required for the product temperature B to drop from the upper limit temperature T20 to the cold storage temperature ↑2 is also significantly reduced.

It should be noted that the present invention can be applied to various types of showcases other than the flat oven oven case shown in the drawings, and similar effects can be obtained.

〔Effect of the invention〕

As explained above, according to the operation control method of the silicone case according to the present invention, in addition to significantly shortening the defrosting time, the rise in product temperature due to defrosting of the products stored in the refrigerator, as well as the temperature By reducing the time exposed to rising temperatures, it is possible to prevent product freshness from deteriorating and maintain stable quality.

[Brief explanation of drawings]

FIG. 1 is a time chart of operation control according to an embodiment of the present invention, FIG. 2 is a pattern diagram of the number of operating fans corresponding to each operation mode of the showcase, and FIG. 3 is a cooler corresponding to FIG. Fig. 4 is a schematic diagram of the configuration of a flat oven showcase to which the present invention is applied, and Fig. 5 is a diagram of a cooler corresponding to each operation mode using a conventional operation control method. , In Figure 0, which is a transition chart of temperature changes of products stored in the warehouse, l: case body, 4: cold air circulation duct, 52 cooler, 6
: Defrost heater, 7: Fan unit, 7A. 7B. 7C: Blower fan, controller. Refrigerator 1st page dormitory 2nd stage 3rd cold insulation-←-pork frost-book one round; and figure 5

Claims (1)

[Claims] 1) A cooler, defrost heater, and fan unit were installed in the cold air circulation duct partitioned between the outer box and inner box of the case body, and when defrosting, the cooler was stopped and the defrost heater heated. An operation control method for a cold air circulation type showcase that defrosts a cooler by blowing warm air, the fan unit is equipped with at least three or more blowing fans, and the cooling storage and
An operation control method for a cold air circulation type showcase, characterized in that the operation pattern of the blower fans corresponding to each operation mode of defrosting and pull-down is set as defrosting > cold storage > pull-down, and the operation of each blower fan is switched and controlled. .